to buy a camera lens off craigslist?
Ok, this is what you do. 1. Heft the lens. There shouldn’t be any rattling in the focus ring. The outside should be clean. If there are scratches or white patches in the rubber, that’s fine, but negotiate for a lower price. 2. Turn the focus ring. It should move smoothly and easily, without any sticking spots. It shouldn’t rattle. Turn the aperture ring from f/2.8 to f/22. It should move smoothly, and you should see the aperture open and close when you look through the lens. 3. Look at the front element at an angle to a strong light source so that you can see the coating. It should have a consistent finish with no marks, scratches, swirls, or patches with no coating. You can see the coating in this picture (this is a lens I sold on ebay several months ago). If you see some small specks, it’s fine, but you should negotiate for a lower price. Scratches won’t show up on your images, but it’ll lower the resale price of the lens. Same with cle
You should know too that a lens like that was originally designed for 35mm film SLR cameras and that when you use it on a DSLR there will be a crop factor of about 1.55 owing to the difference in size between a frame of 35mm and the size of the sensor in your camera. That turns a 28mm into a 43mm basically, which most people would probably consider a little tight for shooting landscapes.
